Metamorphic rocks from Córdoba (Argentina) and the alkali-silica reaction (ASR).

FRANSISCO LOCATI; EDGARDO BALDO; SILVINA MARFIL; OSCAR BATIC

Auckland

Congreso; 11th IAEG (International Association of Engineering Geology Congress).; 2010

IAEG

The “Sierras Pampeanas de Córdoba” (Argentina) is an igneous-metamorphiccomplex affected by shear zones. The deformation varies from one sector to another producingmicrostructures that affect the internal order and the size of the crystals, generating sitessusceptible to suffering the attack of alkaline solutions. This process, known as alkali-silicareaction (ASR), occurs between cryptocrystalline, strained and/or amorphous silica compoundsand the alkalis in the concrete pore solution, and forms a gel that increases its volumeproducing cracks and concrete deterioration.To evaluate the potential reactivity of rocks from the Córdoba region, the petrographicmethod (ASTM C 295), the accelerated mortar bar test method (ASTM C 1260) and the determinationof dissolved silica (ASTM C 289) were carried out. The preliminary results allowdetermining a positive linear correlation (R2 = 0.86) between the expansion in mortar barsand leached silica. These values grow with deformation intensity increment in quartz-bearingrocks.